RF ablation is used in multiple applications to treat numerous diseases. Traditionally, RF ablation has been applied to heart tissue to treat cardiac arrhythmia (e.g., atrial fibrillation) by destroying abnormal heart tissue. This procedure is performed on thousands of patients annually around the world and is becoming more widely accepted as an increasing number of reports show safety and efficacy. Reported success rates for catheter ablation therapy for cardiac arrhythmias exceed 95% for RF ablation of most accessory pathways and AV nodal reentry. RF ablation is also well known for treating tumors in the liver as well as the lung, breast, pancreas, bile duct, bone, and kidney. Additionally, RF ablation has been used to treat varicose veins, uterine fibroids, and as a method for pain management. RF ablation is the most commonly used minimally invasive therapy in the United States to treat hepatocellular carcinoma (HCC) and liver metastases. Percutaneous RF ablation therapy has been shown to be a cost-effective treatment when compared to palliative care for malignant hepatic neoplasms.
Current RF ablation devices require electrodes to be hard wired to an RF generator. These electrodes can then be delivered into the patient percutaneously. Then the RF generator is used to adjust the power (and thus the temperature) that the electrode delivers to the tissue of interest. MRI is a rapidly growing imaging technique and it is beginning to be used intraoperatively. MRI provides a high soft-tissue contrast which allows physicians to delineate tumor tissue and the surrounding anatomy much better than ultrasonography and computed tomography. MRI is sensitive to thermal effects which allows for monitoring of the RF ablation, commonly referred to as real time thermography. While MRI does not emit ionizing radiation, it does pose safety risks concerning magnetically induced displacement force. This concern increases when the MR system is used intraoperatively causing MR unsafe objects to be in the room close to the MR system, such as an RF generator.
Thus, there is a need for improved techniques that permit RF ablation in an MRI without the difficulties of using an external RF generator or other potentially hazardous equipment.